JPH1077992A - Vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate the abnormality of a pump main body from the abnormality of an exhaust port side in a vacuum pump. SOLUTION: This vacuum pump is provided with a rotation detector 6 for genrating a pulse in proportion to the rotation speed of the motor of a vacuum pump, a frequency voltage converter 20 for converting to a voltage value in proportion to the rotation speed, a standard voltage generator 30 for generating a standard voltage value in response to the allowable rotation speed of the motor, a first abnormality detector 50 for detecting the abnormality of a pump in comparison with the voltage value and standard voltage value, a pressure detector 7 for detecting the exhaust pressure of the exhaust port side of the vacuum pump and a second abnormality detector 51 for detecting the abnormality of the exhaust port side in comparison with the exhaust pressure and the standard pressure. A pump main body is monitored by monitering the rotation speed of the motor and the exhaust port side is monitored by monitering the pressure of the exhaust port and the abnormality detection of the exhaust port side is carried out at the abnormality detection time of the motor and when the abnormality is detected on the exhaust port side by this abnormality detection, the abnormality of the exhaust port side is judged and when the abnormality is not detected in the exhaust port side, the abnormality of the pump main body is judged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum pump such as a turbo molecular pump, and more particularly to a function of detecting an abnormality of a vacuum pump.

[0002]

2. Description of the Related Art A vacuum pump such as a turbo molecular pump rotates a rotor by a motor and discharges gas molecules sucked from an intake port to an exhaust port side, thereby suctioning the intake port side to a vacuum state. The locations that cause such a vacuum pump abnormality can be roughly classified into the pump body and the exhaust port side.

[0003] In the pump body, there is a possibility that an abnormality may occur in a mechanical portion such as an electric system, an internal piping system, or a bearing portion. For example, disconnection of a wiring for driving a motor or frictional resistance of a rotary shaft or the like may occur. When the load increases due to the increase in the amount of the reaction product or the adhesion of the reaction product in the piping system, an abnormality such as a decrease in the rotation speed of the motor occurs. Also, on the exhaust port side, there is a possibility that an abnormality may occur at a connection part of the exhaust system or the like. For example, when the conductance increases due to a leak or the like in a pipe on the exhaust port side, an abnormality such as an increase in pressure on the exhaust port side occurs.

Conventionally, the abnormality of the vacuum pump is detected by monitoring the rotation speed of the pump. When the rotation speed of the motor for driving the pump becomes lower than a predetermined rotation speed, an abnormality is displayed by an alarm or the like. And the brakes are activated to stop the vacuum pump.

[0005]

An abnormality in the rotational speed of the motor of the vacuum pump occurs due to an abnormality in the electric system, internal piping system, and mechanical parts of the pump body, or an abnormality in the exhaust system on the exhaust port side. May occur as a factor. However, since the conventional vacuum pump detects an abnormality by monitoring the rotation speed of the motor, it is difficult to identify whether the detected abnormality is located on the pump body or on the exhaust port side. There is a problem that is. For this reason, it is not possible to quickly deal with the vacuum pump after the abnormality is detected. Accordingly, it is an object of the present invention to solve the above-described problems of the conventional vacuum pump, and to provide a vacuum pump capable of distinguishing between an abnormality in the pump body and an abnormality on the exhaust port side and determining an abnormal portion. I do.

[0006]

A vacuum pump according to the present invention comprises:
The pump speed is monitored by monitoring the rotation speed of the motor that drives the rotor, the pressure at the exhaust port is monitored, and the exhaust port side is monitored. If an abnormality is detected on the exhaust port side, it is determined that an abnormality has occurred on the exhaust port side, and if no abnormality has been detected on the exhaust port side, it is determined that an abnormality has occurred in the pump body. Thus, the abnormality of the pump body and the abnormality of the exhaust port side are identified.

[0007] In a vacuum pump, the causes of a decrease in the rotation speed of the motor are usually an abnormality in the pump body and an abnormality on the exhaust port side. It cannot be identified whether it is on the exhaust port side. Therefore, in the present invention, it is determined whether the abnormal portion is the pump body or the exhaust port side by monitoring the pressure on the exhaust port side in addition to monitoring the rotation speed of the motor.

[0008] In order to identify the abnormal portion, the vacuum pump according to the present invention includes a rotation detector that generates a pulse proportional to the rotation speed of a motor that drives a rotor of the vacuum pump;
A frequency-voltage converter that converts the number of pulses per fixed time into a voltage value, a reference voltage generator that generates a reference voltage value corresponding to the allowable rotation speed of the motor, and a pump that compares the voltage value with the reference voltage value A first abnormality detector for detecting abnormality,
A pressure detector for detecting an exhaust pressure on the exhaust port side of the vacuum pump, and a second abnormality detector for comparing the exhaust pressure with a reference pressure to detect an abnormality on the exhaust port side; Based on the detection output of the abnormality detector, an abnormal part between the pump abnormality and the abnormality on the exhaust port side is identified.

The frequency voltage converter converts the pulse from the rotation detector into a voltage value proportional to the rotation speed, and the first abnormality detector compares the voltage value with the reference voltage value to determine the rotation speed of the motor. To detect abnormalities. The reference voltage value is a voltage value corresponding to the allowable rotation speed of the motor.If the rotation speed of the motor decreases, the converted voltage value also decreases. Abnormality detection. The second abnormality detector detects that the pressure on the exhaust port side rises and exceeds the reference pressure, and determines that the abnormality on the exhaust port side is detected.

In a first embodiment of the present invention, when both of the first abnormality detector and the second abnormality detector detect an abnormality, the abnormality is regarded as an abnormality on the exhaust port side. Only when an abnormality is detected is determined to be an abnormality of the pump main body, an abnormal portion is identified.

In a second embodiment of the present invention, the reference voltage generator starts integration of a constant voltage in synchronization with the start of rotation of the motor, and sets an upper limit of integration when the motor reaches a steady rotation speed. A voltage value is generated, whereby a voltage value corresponding to the rotation speed of the motor can be generated.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. One embodiment of the vacuum pump of the present invention will be described with reference to the schematic block diagram shown in FIG. A vacuum pump 1 shown in FIG.
And a monitor 3. An intake pipe 4 connected to a vacuum vessel or the like is provided on an intake port side of the pump body 2, and an exhaust pipe 5 for discharging exhaust gas is provided on an exhaust port side. The pump body 2 has a built-in rotation system including a rotor and a motor for driving the rotor, and a rotation sensor 6 attached to this rotation system detects the rotation speed of the motor. A pressure sensor 7 is attached to the exhaust port side of the pump body 2 to detect pressure on the exhaust port side.
The monitor 3 receives the pulse signal detected by the rotation sensor 6 and the signal detected by the pressure sensor 7, and
In addition to displaying on the display device 11 through the pressure display 9 and inputting it to the abnormality detection device 10, the abnormality is detected and the location of the abnormality is identified, and is displayed on the display device 11 or other display means.

FIG. 2 is a block diagram for explaining an example of the configuration of the abnormality detection device. In FIG. 2, the abnormality detection device 10 includes a part that detects an abnormality in the pump body, a part that detects an abnormality on the exhaust port side, and a part that identifies an abnormal part between the abnormality in the pump body and the abnormality on the exhaust port side. Is provided. The part for detecting an abnormality of the pump body is constituted by blocks with reference numerals of 20s and 30s in FIG. 2, and the part for detecting abnormality on the exhaust port side is indicated by blocks denoted by 40 in FIG. 2. FIG. 2 is a block diagram showing a portion for identifying an abnormal portion between an abnormality in the pump body and an abnormality on the exhaust port side.
It is composed of blocks with reference numerals in the 50's. The part that detects the abnormality of the pump body is a rotation sensor 6.
F / V converter (frequency / voltage converter) 20 which receives a pulse signal from the converter and converts it into a voltage value proportional to the rotation speed
And a reference voltage generator 30 for obtaining a voltage value corresponding to the allowable rotation speed of the motor.

The F / V converter 20 includes a Schmitt circuit 21
And monostable multivibrator 22 and integrating circuit 2
3 are connected in series. The Schmitt circuit 21
The pulse signal from the rotation sensor 6 is converted into a rectangular pulse signal. The number of the rectangular pulse signals is a number corresponding to the rotation speed. Further, the rectangular pulse signal is passed through a monostable multivibrator 22 to be converted into a pulse signal having a constant pulse width. The pulse signals thus obtained have a constant pulse width and a number proportional to the rotation speed of the motor. Further, the obtained pulse signal is integrated by the integration circuit 23 to obtain a voltage value proportional to the rotation speed of the motor.

FIG. 3 is a diagram for explaining a comparison between the detected voltage of the rotation sensor and the reference voltage. The detected voltage value V obtained by the F / V converter 20 is, for example, as shown in FIG. It is represented by a solid line. The detected voltage V in FIG.
5 shows the elapsed state after the start of driving of the motor, and the voltage increases in accordance with the acceleration of the motor. The reference voltage generator 30 is configured by connecting a reference power supply 31 for generating a constant voltage to an integration circuit 32 via a start switch 33, and further connecting a limiter circuit 35 to the integration circuit 32. The integration circuit 32 includes a stop switch 34.

The start switch 33 is turned on in synchronization with the start of driving of the motor of the pump body, connects the reference power supply 31 and the integrating circuit 32, and integrates the voltage in the integrating circuit 32 with a predetermined time constant. This time constant is set according to the acceleration characteristic of the allowable rotation speed of the motor. Therefore, the voltage value output by the integration circuit 32 is a value corresponding to the allowable rotation speed after the motor starts to be driven, and is a reference value for detecting abnormal rotation of the motor. Since the motor has a steady rotation speed after a predetermined time has elapsed, the limiter circuit 35 is driven at the time when the motor reaches the steady rotation speed to keep the reference voltage value at a constant value. At this time, the stop switch 34 of the integrator 32 is operated to stop the integration process of the integrator. As a result, the reference voltage Vc generated by the reference voltage generator 30 becomes a voltage as indicated by a broken line in FIG.

The abnormality of the pump body is detected by the F / V converter 2
The comparison is performed by the comparator 50 comparing the detected voltage value V obtained at 0 with the reference voltage Vc generated by the reference voltage generator 30. The detected voltage value V corresponds to the rotation speed of the motor, and the reference voltage Vc corresponds to the allowable rotation speed of the motor. Therefore, when the pump body is operating normally, the detected voltage value V is larger than the reference voltage Vc as shown in FIG. Therefore, the comparator 50
, The two voltage values are compared, and when the detected voltage value V becomes equal to or lower than the reference voltage Vc, it is determined that the abnormality is detected.

FIGS. 3 (b) and 3 (c) are schematic examples of abnormality detection. FIG. 3 (b) shows a case where the rotation speed becomes lower than the allowable rotation speed during acceleration of the motor, and FIG. This is the case where the rotation speed becomes equal to or lower than the allowable rotation speed at the time of the steady rotation speed, and the comparator 50 outputs an abnormality detection signal at the time indicated by the arrows in the figure.

The portion for detecting an abnormality on the exhaust port side is provided with a reference voltage generator 40. The reference voltage generator 40 is a device that generates a voltage value corresponding to an abnormal level of pressure on the exhaust port side. FIG. 4 is a diagram for explaining a comparison between the detection output of the pressure sensor and the reference voltage. Exhaust port side pressure P
During normal operation, the pressure is within the allowable range in the figure, and when an abnormality such as a leak occurs on the exhaust port side, the pressure rises. In the abnormality detection on the exhaust port side, a pressure value determined to be abnormal is set as an abnormal level, and when the detected pressure P exceeds the abnormal level is detected, the abnormality is detected. The abnormality detection on the exhaust port side is performed by comparing the detected voltage of the pressure sensor 7 with the reference voltage generated by the reference voltage generator 40 by the comparator 51.

The abnormal signal output device 52 is a part for identifying an abnormal portion between an abnormality in the pump body and an abnormality on the exhaust port side. An abnormality is detected on the exhaust port side.If an abnormality is detected on the exhaust port side, it is determined that the abnormality is on the exhaust port side.If no abnormality is detected on the exhaust port side, it is determined that the pump body is abnormal. And abnormalities on the exhaust port side are identified.

Next, using the flowchart for explaining the abnormality detection procedure in FIG. 5 and the comparison diagram between the detected voltage and the reference voltage in FIGS. Will be described. The rotation sensor 6 detects the rotation speed of the motor of the vacuum pump, and outputs the rotation pulse obtained from the rotation sensor 6 to the F / V converter 20 in the abnormality detection device 10.
(Step S1). The F / V converter 20 processes the input rotation pulse to obtain a detection voltage V corresponding to the rotation speed, and inputs the detection voltage V to one input terminal of the comparator 50 (step S2). The reference voltage Vc corresponding to the allowable speed is input from the reference voltage generator 30 to the other input terminal of the comparator 50, and is compared with the detection voltage V (step S3).

In the comparison in step S3, the detection voltage V
Is greater than the reference voltage Vc, the motor is rotating normally and the pump body is determined to be normal. This state is
6A and 7A, the solid line representing the detection voltage V is a portion above the broken line representing the reference voltage Vc. On the other hand, when the detected voltage V is smaller than the reference voltage Vc in the comparison in step S3, it is determined that the motor is rotating abnormally and the vacuum pump is in an abnormal state. This state is a part where the solid line is below the broken line in FIGS. 6 (a) and 7 (a). The abnormal state of the vacuum pump may be an abnormality in the pump body or an abnormality on the exhaust port side. Therefore,
In the next step S4, an abnormal part is identified.

In step S4, the comparator 51 compares the pressure P on the exhaust port side with an abnormal level. If a pressure abnormality on the exhaust port side is detected in the comparison in step S4, it is determined that the abnormal part of the vacuum pump is on the exhaust port side, and an abnormality on the exhaust port side is displayed. FIG. 6 shows a case where the exhaust port side is abnormal. When the rotational speed is detected to be abnormal in FIG. 6 (a), the exhaust port pressure exceeds the abnormal level in FIG. 6 (b). It is determined that the abnormal point is on the exhaust port side (step S5).

In the comparison in step S4, if no abnormal pressure on the exhaust port side is detected, it is determined that the abnormal part of the vacuum pump is on the pump main body side, and the abnormality on the pump main body side is displayed. FIG. 7 shows a case where the pump body side is abnormal. When the abnormality is detected in the rotational speed in FIG. 7 (a), the exhaust port side pressure is in the allowable range in FIG. 7 (b). It is determined that the location is the pump body (step S6).

[0025]

As described above, according to the vacuum pump of the present invention, it is possible to discriminate abnormalities between an abnormality in the pump body and an abnormality on the exhaust port side.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram for explaining one embodiment of a vacuum pump of the present invention.

FIG. 2 is a block diagram illustrating an example of a configuration of an abnormality detection device according to the present invention.

FIG. 3 is a diagram for explaining a comparison between a detection voltage of a rotation sensor and a reference voltage.

FIG. 4 is a diagram for explaining a comparison between a detection output of a pressure sensor and a reference voltage.

FIG. 5 is a flowchart illustrating a procedure for detecting an abnormality of the vacuum pump according to the present invention.

FIG. 6 is a comparison diagram for explaining a rotation speed and a pressure when there is an abnormality on the exhaust port side.

FIG. 7 is a comparison diagram for explaining a rotation speed and a pressure when there is an abnormality on the pump body side.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum pump, 2 ... Pump body, 3 ... Monitor, 4 ... Intake pipe, 5 ... Exhaust pipe, 6 ... Rotation sensor, 7 ... Pressure sensor,
Reference numeral 8: rotation display device, 9: pressure display device, 10: abnormality detection device, 11: display device, 20: F / V converter, 21: Schmitt circuit, 22: monostable multivibrator, 23, 32: integration circuit, Reference numerals 30, 40: reference voltage generation circuit, 31: start switch, 33: stop switch, 34: limiter circuit, 50, 51: comparator,
52: Abnormal signal output device.

Claims (1)

[Claims] 1. A rotation detector for generating a pulse proportional to the number of rotations of a motor for driving a rotor of a vacuum pump, a frequency-to-voltage converter for converting the number of pulses per fixed time into a voltage value, A reference voltage generator that generates a reference voltage value corresponding to the permissible rotation speed; a first abnormality detector that compares the voltage value with the reference voltage value to detect an abnormality of the pump; A pressure detector for detecting an exhaust pressure; and a second abnormality detector for comparing the exhaust pressure with a reference pressure to detect an abnormality on the exhaust port side.
A vacuum pump for identifying an abnormal portion between a pump abnormality and an abnormality on the exhaust port side based on a detection output of a second abnormality detector.